Emulsions prepared with cationic emulsifier



PRESSABILITY SECONDS Nov. 30, 1965 M. J. BORGFELDT NH4 c| PERCENT INVENTOR MERTON J. BORGFELDT United States Patent 3,220,953 EMULSIUNSPREPARED WITH CATIONIC EMULSIFIER Merton J. Borgfeldt, 64 Sunview Drive,San Francisco, Calif. Filed Aug. 2, 1962, Ser. No. 217,236 2 Claims.(Cl. 252-31ll.5)

This application is a continuation-in-part of Serial No. 2,060, filed bythe applicant in the US. Patent Office :on January 12, 1960, and nowabandoned, which, in turn, is a continuation-in-part of applicationSerial No. 693,590, by the same applicant, filed in the US. PatentOffice on October 31, 1957, later abandoned.

This invention relates to bituminous emulsions of th oil-in-water type.It also relates to emulsions of the oilin-water type in which thedisperse phase, instead of being a bituminous material, is some otherthermoplastic, organic, water-insoluble, water-emulsifiable material.

Bituminous emulsions of the oil-in-water type are widely used and havebeen used extensively for many years in paving work and the like. Suchemulsions are mixed with mineral aggregate, and when such an emulsionbreaks or dries, it deposits the bituminous material on the aggregate toact as a binder. Emulsions of this character are advantageous because,among other things, they are noninflammable, they do not require theapplication of heat to melt solid bitumen, and they do not require theuse of a volatile, inflammable thinner. Bituminous emulsions as usedheretofore have, however, certain disadvantages, among which may bementioned the following:

It is necessary that an emulsion remain emulsified during storage andshipment and be stable against breakdown on pumping and agitation. Yet,when an emulsion is mixed with an aggregate, it is desirable that theemulsion break quickly and deposit the bitumen rapidly on the aggregateparticles. It is difiicult to achieve a delicate balance between anemulsion which is stable in storage, shipment, agitation and pumping,but which when mixed with aggregate will break quickly and deposit thebitumen on the aggregate particles. These difliculties are aggravated ifthe aggregate is moist and/ or if it is of a hydrophilic, siliceousnature. Wet conditions and the requirement that a hydrophilic, siliceousaggregate be used, are circumstances that are frequently encountered inpractice.

Emulsifying agents employed heretofore have been predominantly of theanionic type, which is typified by the sodium salt of a fatty acid suchas oleic acid. In sodium oleate the oil-solubilizing group is containedin the anion, RCOO. It is the anion of this type of emulsifying agent,which contains the oil-solubilizing group (represented by R) and whichbecomes afiixed to or associated with the dispersed bitumen particles.For this reason this type of emulsifying agent is known as anionic or asthe anion-active type.

More recently it has become known that cationic or cation-activeemulsifiers may be used and that they have certain important advantages.

Particularly, it is now known that salts of quaternary nitrogen basesare excellent cationic emulsifying agents. These cationic salt materialshave the general formula r Rr-III-Rg X R4 in in which R R R and R areorganic radicals, each having a carbon-nitrogen linkage to the nitrogenatom, X is an anion whose valance does not exceed 2, and m and n aresmall integers which indicate the molar proportions of the cation andanion required to form the respective salt. Preferred emulsifying saltsare those in which the organic radicals R R R and R are alkyl, alkenyl,hydroxyalkyl, aryalkyl and alkylaryl radicals of 1 to 24 carbon atomsand heterocyclic groups of 4 to 10 carbon atoms in which from 2 to 3 ofthe nitrogen valences are shared .by two carbon atoms in a singleheterocyclic group. In all of these salts of quaternary nitrogen bases,suitable for use as cationic emulsifiers in the preparation ofoil-in-water type emulsions, the aggregate number of carbon atoms in thecationic portion of their molecule should be large enough to impartoil-solubility and emulsifying properties, and preferably should beequal to not less than 20 and not more than 30 carbon atoms. In otherwords, this class of cationic quaternary nitrogen-containing compoundsis formed by salts of tetra-substituted ammonium bases and by salts ofheterocyclic nitrogen bases, such as pyridinium, quinolinium,isoquinilinium, morpholinium, piperidinium, imidazolinium, and otherlike quaternary nitrogen-containing bases. The anion may be'either ahalide (X), a methosulfate (SO4CH3 a nitrate (NO or the like ion.Monovalent anions are preferred, particularly the halide anions.

Numerous cationic quaternary nitrogen-containing emulsifiers may beemployed for the preparation of cationic oil-in-water type emulsions.Among them, to mention but a few, are:

N,N-dimethyl-N-benzyl-N-octadecyl ammonium chlorideN,N-dimethyl-N-hydroxyethyl N dodecyl ammonium chlorideN,N-dimethyl-N-benzyl-N-octadecenyl ammonium chlorideN,N-dimethyl-N-benzyl-N-dodecyl ammonium chlorideN,N-dimethyl-N-hydroxyethyl-N-benzyl ammonium chloride Hexadecylpyridinium chloride Hexadecyl triethyl ammonium bromide Otcadecylbenzyltrimethyl ammonium methosulfate Isopropylnaphthyl trimethyl ammoniumchloride Octadecyl pyrodinium bromide1-(2-hydroxyethyl)-2-heptadecenyl-l-(4-chlorobutyl) imidazoliniumchloride Hexadecyl methyl piperidinium methosulfate Dodecyl hydroxyethylmorpholinium bromide Among the quaternary nitrogen-containing materialsavailable in commerce as cationic emulsifiers for the preparation ofoil-in-water type emulsions there are quarternary ammonium salts, suchas quaternary ammonium halide materials sold by O ronite ChemicalCompany of San Francisco, California, under the trademarks ATM- 50 andADE-50; materials sold by Armour and Company under the several Arquadtrademarks; materials sold by National Aluminate Company under theseveral Nalquat trademarks; certain quaternized materials developed andsold by the Society of Chemical Industry in Basel, Switzerland, underthe several Sapamine trademarks, and many others.

The active cationic component of these materials contains thecharacteristic positively charged quaternary nitrogen configuration inwhich the aggregate of carbon atoms of R R R and R is sufiioient toimpart oil-solubility and emulsifying properties, and preferably isequal to not less than 20 and not more than 30 carbon atoms.

Best emulsification can be achieved with those among the aforesaidquaternary nitrogen-containing materials in which the active cationiccomponent contains at least one long aliphatic hydrocarbon chain of notless than 12 and not more than 24 carbon atoms, such as an alkyl or analkenyl chain. This latter chain may be derived from a mixture oforganic materials such as tallow, soybean oil, lard, etc.

It is a known advantage of the above and other like cat-ionicemulsifiers that they produce oil-in-water bituminous emulsions whichdeposit the bitumen on aggregate more quickly and more effectively thando emulsions in which the emulsifying agent is of the anion-active type.A convincing demonstration of this phenomenon can be carried out in thefollowing manner:

Two similar quantities of the same lot of siliceous hydrophilicaggregate are taken. Each is wetted with a predetermined amount ofwater. Then a predetermined amount of an asphalt emulsion is added toeach of the wetted samples of aggregate, the emulsions being identicalexcept that in one case the emulsifying agent is of the cationic typeand in the other it is of the anionic type. The emulsion and aggregateare mixed together for about three minutes. It will be observed that,during mixing, an anionic bituminous emulsion, i.e., an emulsion madewith an anionic emulsifier and characterized by an alkaline pH above7.0, and preferably above 9.0, will not break down. After the lapse ofthree minutes of stirring, if a stream of flowing water is used to washthe aggregate, it will be observed that the water washes the anionicemulsion off of the aggregate and that the aggregate is virtuallyuncoated. This demonstrates that an anionic emulsion of the usual typerequires, under the test conditions, a relatively long period of timefor deposition of the bitumen.

By way of contrast, it will be observed that during mixing of the wettedaggregate with a cationic bituminous emulsion, i.e., an emulsioncharacterized by a pH below 7.0, and preferably between 4.0 to less than7.0, the aggregate becomes coated by reason of breakdown of the emulsionand deposition of the bitumen on the aggregate particles. The deposit ofbitumen acts as a binder and increases the viscosity of the mix. At theend of three minutes, the washing test described above is repeated. Itwill be observed that the aggregate particles are thoroughly andcompletely coated with the bitumen.

The test conditions just described, which will be refered to as theStone Coating Test, simulate conditions encountered in practice. Forexample, in many cases the available aggregate is of a siliceous,hydrophilic character and is very difficult to coat with bitumen from ananionic emulsion. Also, the aggregate is frequently wet, which makescoating even more difficult.

Notwithstanding the advantages above described, cationic emulsifiers andemulsions have certain drawbacks and disadvantages. Thus, cationicemulsifiers are considerably more expensive than anionic emulsifiers.Moreover, the same balance as in the case of anionic emulsions isdesired in a cationic bituminous (asphalt) emulsion, i.e., the emulsionshould have a uniformly small particle size and should not deposit anexcessive amount of large partciles or shot on a screen in ASTM -D 24455Sieve Test; it should remain stable in storage and when agitated andpumped, but should break down readily and speedily upon admixture withaggregate to coat the aggregate effectively. This balance is difficultto achieve.

The aforementioned cationic quaternary nitrogen-containing salts,although a number of them have been described in the art as valuableaddition agents to nonemulsified bitumen, and as emulsifiers therefor,e.g., by Dohse and Spoun in their US. Patent No. 2,191,295, as a matterof fact frequently fail to provide emulsions that remain stable instorage and, particularly, while being handled and pumped, prior to theapplication of the emulsion to the aggregate, and thus fail to achieve asatisfactory coating of this latter by the bitumen, such as an asphalt.

It is an object of the present invention to provide improvements incationic bituminous emulsions of the character described.

It is a further object of the invention to provide a means of improvingthe results of the aforementioned Sieve Test and, particularly, pumpingand handling stabilities, in other words, to provide a means of loweringviscosity, without inducing, however, a premature breakdown of theemulsion, and without adversely affecting thereby the formation of asatisfactory coating of bitumen on the aggregate.

These and other objects of the invention will be apparent from theensuing description and the appended claims.

I have found that the properties of cationic emulsions, that is, ofoil-in-water type emulsions of bitumen and the like materials, in whichthe effective or major emulsifying agent is a salt of a quaternarynitrogen base, can be markedly improved by the introduction of a smallamount of any one (or of more than one) of certain additive salts.

These properties include: emulsion quality, that is smooth texture,substantial freedom from graininess, absence of settlement and skinformation; high plating (deposition) ability; stability in storage;mixing stability, that is while mixing the emulsion with the aggregate;pumping stability; lower viscosity suitable for coating and paving work;much higher degree of adhesion of the bituminous binder component to theaggregate surface; higher mat strength of the correspondingemulsionaggregate mixes, etc.

These additive salts, as they will be referred to hereinafter, arewater-soluble salts of the type Me A in which Me represents the ammoniumradical (NI-I4), an alkali metal, such as lithium, sodium or potassiumor an alkaline earth metal, such as magnesium, barium or calcium; inwhich A represents a monoor divalent anion; and in which a and bindicate the molar proportions of Me and A required to form therespective salt.

Preperably, where Me is divalent (e.g., Mg++), A is monovalent. Mostadvantageously, both Me and A are monovalent, in which case a and b areeach equal unity.

Examples of cations in operative additive salts are: the ammonium,lithium, sodium, potassium, magnesium, calcium and barium cations.Examples of corresponding anions are: the fluoride, chloride, bromide,iodide, thiocyanate, sulfate, acetate, propionate, benzoate, lactate,basic citrate and sulfonate anions. The corresponding operative additivesalts are, for instance, ammonium chloride, ammonium sulfate, ammoniumthiocyanate, sodium chloride, sodium thiocyanate, sodium acetate,various water-soluble low molecular weight sulfonates, such as sodiumbenzene sulfonate and sodium naphthalene-,B-sulfonate, lithiumthiocyanate, lithium chloride, potassium chloride, potassiumthiocyanate, sodium sulfate, calcium sulfate, calcium thiocyanate,calcium chloride, magnesium chloride and barium chloride.

I While all of the aforementioned water-soluble salt additives will tendto improve the quality and the performance of the emulsions of myinvention, and, in particular, their pumping stability and mixingstability, some of them will be more suitable than others in enhancing aparticular quality or performance property (or properties) of anemulsion, depending on the particular, more or less efiective quaternarynitrogen-containing emulsifier. Thus a chloride, such as ammoniumchloride, will be more effective than a corresponding sulfate (NH SO inimproving emulsion quality (lack of graininess, homogeneous texture,etc.), while the sulfate will tend to impart better plating. In fact, asa general rule, salts of monovalent anions are more beneficial toemulsion quality than salts of divalent anions, contemplated by myinvention.

These additive salts employed in accordance with the present inventionare preferably used in a smaller amount than the cationic emulsifiereffective in preparing the cationic bituminous emulsion, and usually inamounts from about 0.01 to about 0.25%, based on the weight of finishedemulsion. Again, however, more or less may be employed depending uponfactors, such as the cost of the cationic quaternary nitrogenemulsifier, the nature and amount of the dispersed material, etc.

A particularly preferred group of operative salts is one of the ammoniumand alkali metal thiocyanates, the addition of which in amounts fromabout 0.01 to about 0.25%, and preferably from about 0.025 to about0.20% by Weight, based on the finished emulsion, markedly enhancesstability of the cationic bituminous (asphalt) emulsion upon agitation,as by stirring, and in pumping.

Another remarkably satisfactory group of operative additive salts isformed by alkali metal acetates and propionates. When these lowmolecular weight carboxylates, and among them particularly sodiumacetate, are present in the cationic bituminous emulsions of theinvention in the aforementioned range of amounts of from about 0.01 toabout 0.25% and preferably from about 0.025 to about 0.20% by weight,the mixing stability of cationic bituminous emulsions is markedlyimproved. In other words, their addition improves ability of mixing theemulsion with siliceous stone aggregate or sand and of depositing on thesurface of this aggregate a perfect, durable and firmly adherent coatingof the bituminous binder, such as an asphalt. At the same time, theability of the emulsion to withstand agitation and particularly itsability to be pumped Without breaking down are likewise remarkablyenhanced.

Likewise, chlorides of ammonium, alkali metal, and alkaline earth metalanions, when used in the same range of proportions (about 0.01 to about0.25%, and preferably about 0.025 to about 0.20% by Weight), improvesubstantially the stability of cationic bituminous emulsions not only instorage, but also when subjected to agitation and, particularly, topumping. Also the presence of these chlorides is noted to extend themixing stability; that is, ability of being mixed with stone aggregatewithout too quick a breakdown.

The additive salts of my invention, and particularly the preferred ones,significantly improve the quality of cationic emulsions prepared withthe aid of the aforedescribed emulsifiers and markedly enhance theperformance qualities of these emulsions and/or their mechanicalstability, i.e., stability while being mixed with the aggregate prior tobeing applied to the road surface.

The disperse phase of the emulsion is a bituminous material, such as anasphalt (which may be a natural asphalt or may be derived from therefining of petroleum as by steam refining and/or air blowing),gilsonite, coal tar or coal tar pitch. However, the disperse phase maybe any other insoluble, thermoplastic, organic material which isemulsifiable in water by means of a cationic emulsifier, for example,parafiin wax, acrylic resins, polyethylene resins, Vistanex or alkydresins.

The water and the bitumen may be employed in varying proportions, forexample, about 30 to about 70 parts by weight of water and about 70 toabout 30 parts by weight of bitumen, e.g., an asphalt, preferably fromabout 50 to about 70% by weight.

The principal emulsifying agent, which will frequently be the onlyactive component of the emulsifier is a salt of a quaternary nitrogenbase, containing the characteristic ionogenic group as definedhereinbefore in this specification.

The emulsifier material may consist entirely of an active cationic saltof a quaternary nitrogen base, or may also contain-some impurities, suchas acyl chlorides and amines. It may be also employed in the form of aconcentrated aqueous solution and may contain auxiliary stabilizers inamounts conventionally employed in the trade.

Among the available commercial emulsifier materials, the following maybe employed for the preparation of cationic emulsions in accordance withthe invention:

(1) ATM50. This is the trademark of a product of California ChemicalCo., San Francisco, California, for N-alkyl benzyl-N,N,N-trimethylammonium chloride which has the following formula R c 2H5 in which Raverages about 12 carbon atoms. As in the case of ATM-50, the compoundADE-5O contains minor amounts of the starting materials which, in thiscase, are alkyl benzyl chloride and N,N-diethyl-N-ethanol amine.

(3) Emcol 13-11. This is the trademark of a product of Emulsol ChemicalCorporation of Chicago, Illinois, for N-alkyl benzyl-N,N,N-trimethylammonium chloride having the following formula wherein R averages about12 carbon atoms.

(4) Hyamine 2389. This is the trademark of a product of Rohm and HaasChemical Co., of Philadelphia, Pennsylvania, for N-alkyl methylbenZyl-N,N,N-trimethyl ammonium chloride which has the following formulawherein R averages about 12 carbon atoms.

(5) Arquad T. This is the trademark of a product of Armour and Company,Chemical Division, of Chicago, Illinois, for C C -alkyl trimethylammonium chloride which has the following formula wherein R is a longalkyl chain derived from fallow.

(6) Hyamine 1622. This is the trademark of a product of Rohm and HaasChemical Co., of Philadelphia, Pennsylvania, for di-isobutylphenoxyethoxy ethyl dimethyl benzyl ammonium chloride monohydrate of theformula (7) Arquad S. This is the trademark of a product of Armour andCompany, Chemical Division, of Chicago, Illinois, for C -C alkyltrimethyl ammonium chloride which has the formula wherein R is a longalkyl chain derived from soybean oil.

7 (8) Quatrene AT. This is the trademark of a product of TextilanaCorporation, of Hawthorne, California, for a quaternarynitrogen-containing chloride material of the formula wherein A is a C-alkyl chain derived from stearic acid and G is a polyoxyethylene groupof approximately 5 oxyethylene units.

(9) Nalquat G-9-13. This is the trademark of Nalco Chemical Company ofChicago, Illinois, for 1-(2-hydroxyethyl)-2-heptadecenyl 1 (or 3) (4chlorobutyl) imidazolinium chloride.

It is believed that minor amounts of the starting materials ordinarilyare present in the aforementioned emulsifiers as impurities of noconsequence to their operativeness according to the invention.

These and other suitable cationic emulsifiers may be employed in varyingamounts, generally from about 0.25 to about 1.5%, and preferably fromabout 0.40 to about 1.5% of the active cationic component, based on theweight of the finished emulsion, although more or less may be employeddepending upon factors such as the cost of the emulsifier, itseffectiveness as an emulsifying agent, the amount of bitumen dispersed,etc.

The cationic bituminous emulsions prepared in accordance with theinvention are eminently suitable for various applications in pavingwork. Ordinarily, the working pH of these emulsions ranges from about4.0 to less than about 7.0 and preferably from about 4.5 to about 6.0.This pH permits of applying the cationic emulsions of the invention withsuccess to hydrophilic, siliceous aggregates in sharp contrast With theknown anionic asphalt emulsions characterized by an alkaline pH abovethe neutral point of 7.0, and preferably employed at a pH of from about9.0 to 11.0 and higher. By the same reason, the cationic emulsionscontemplated by the invention are distinguishable from and unlike thepreviously known asphalt emulsions stabilized with the proteins, forinstance, emulsions stabilized with gelatin. These protein-typematerials usually are insoluble at a pH of about 4.0-4.5 and higher and,obviously, are ineffective for stabilizing bituminous emulsions in thepH region from about 4.0 to the neutral point.

The many improvements due to the presence of the various saltsintroduced into cationic bituminous emulsions in accordance with myinvention, in particular, improved emulsion quality and excellentperformance of these emulsions are shown in the following illustrativeexamples and, in the case of chlorides, also by the accompanying drawingobtained by plotting the data observed in using ammonium chloride. Inthe following examples, the percentages of emulsfier are based on 100%active material.

EXAMPLE I This example is given to illustrate improvement resulting fromthe addition of chloride salts in the stability of cationic asphaltemulsions, prepared with quaternary nitrogen-containing emulsifiers,upon subjecting such emulsions to a pumping action as it occurs intransferring the emulsion from a storage tank to mixing and/ orapplication equipment. It also confirms improvement in the adhesion ofthe asphaltic binder to the aggregate.

An emulsion was prepared of 65 parts by weight of Boscan asphalt (asteam-refined Venezuelan asphalt having a penetration of 200/300), inparts of water employing ATM- as the emulsifier in the amount of about0.3% based on weight of finished emulsion. Conventional emulsificationtechnique was employed. To different lots of this emulsion were addedvarying amounts of ammonium chloride. A property denoted as pressabilitywas determined for each of the lots. In determining pressability thefollowing technique was employed:

A large nut is threaded onto a bolt which is rotated by a reversiblemotor equipped with a reversing switch to cause the bolt to spin firstin one direction and then in the opposite direction. The nut is held inplace by a metal container into which the emulsion under test is poured.The motor is started. Since the nut is held against rotation as the boltspins first in one direction and then in the other, the nut will move upand down within the container, thereby simulating a pumping action. Whenthe emulsion breaks due to the pumping operation, it will depositasphalt on the threads of the bolt, thereby binding and hinderingrelative rotation of the bolt and nut. A torque is therefore applied tothe container which increases until it rotates the container. When thecontainer rotates, it opens a limit switch and thereby stops the motor.The lapsed time, which is shown on the ordinate scale of theaccompanying drawing, is a measure of the resistance of the emulsion tothe demulsifying effect of the pumping action. It is referred to aspressability.

It will be seen from the drawing that, by the addition of about 0.04 to0.05% of ammonium chloride, the pressability of the emulsion was greatlyimproved.

Stone coating effectiveness was also improved by the addition ofammonium chloride. Thus, the Stone Coating Test described above wasemployed. The results of the Stone Coating Test are expressed as theextent in percent of total aggregate surface which remains coated withthe binder after the water wash. Adhesion to more than 60% of the wetaggregate surface is considered satisfactory. It was found that a peakof stone coating effectiveness (-100%) was obtained with about 0.033% to0.054% of ammonium chloride.

The results of the Pressability Tests dramatically demonstrated thecriticality of the combination of components necessary for thepreparation of emulsions in accordance with the invention. Thesecationic bituminous emulsions (asphalt-in-water, and the like), whichare formulated using quaternary nitrogen-containing salt emulsifiers andthe water-soluble salts of the particularly specified kind and in theparticular effective amounts, were observed to withstand thedestructive, demulsifying effect to agitation, as it occurs in pumping.This extended stability in pumping is in sharp contrast with theinstability and immediate breakdown in pumping of similar bituminousemulsions prepared with primary aliphatic amine salt emulsifiers,despite the presence therein of like water-soluble salts of ammonium,alkali metal or alkaline earth metal anions. It establishes thepractical superiority of the quaternary nitrogen-containing saltemulsifiers over the primary aliphatic amine salt emulsifiers in theemulsions comprising the aforementioned water-soluble additive salts,such as chlorides, acetates, thiocyanates, sulfates, in regard to actualapplication of these emulsions, permitting their handling afterpreparation and storage, pumping them from tanks through transfer linesinto working equipment, all without the risk of premature breakdown andcostly loss of the bituminous binder component.

The superiority of bituminous emulsions formulated according to myinvention in the practical acid pH range, preferably from about 4.5 toabout 6.9, clearly refutes unsubstantiated assumptions which may haveequated quaternary nitrogen-containing salt emulsifiers with amine saltemulsifiers and, in particular, with primary aliphatic amine saltemulsifiers, such as stearyl amine hydrochloride, despite the well knowndifferences in the solubility of these emulsifier salts.

EXAMPLE II The series of tests shown in this example further illustratesmovements in emulsion properties, particularly in the adhesion of thebituminous binder to siliceous aggregate, when the emulsions preparedwith quaternary nitrogen-containing emulsifiers further containdifferent watersoluble salts in accordance with the invention.

A siliceous, hydrophilic aggregate was employed. Emulsion was preparedfrom a steam-refined, 120-150 penetration asphalt derived from aCalifornia petroleum crude oil. Conventional emulsifying technique wasemployed to emulsify 65 parts by weight of the asphalt in about 35 partsby weight of water. The emulsifying agents employed were Hyamine 2389and ADE-50, which were employed in varying amounts. Two series ofemulsions were, therefore, prepared; one series having having Haymine2389 as the emulsifying agent, and the other series having ADE-50 as theemulsifying agent. Two representative additive salts, a sulfate and achloride,

10 has been broken, the adhesion of asphalt to the aggregate and matstrength, that is to say, the degree to which the particles of aggregateadhere together and resist separation. It is desirable in this test thatmaximum break, maximum adhesion and maximum of mat strength beexhibited,

First any free liquid is poured out, indicating whether any or a part ofthe emulsion did break. Then the remaining solid material in the can isdumped out on a metal screen. If it is in the shape of a big chunk orchunks rather than in the form of individually coated rock particles orchips, the mat strength is rated either as good or fair. By washing thematerial on the screen with a stream of distilled water, one may thenestimate how much asphaltic binder is left adhering to the aggregate.

Table I Additive Salt (NH4)2SO4 percent WSD&P WSD&P

Hyamine 2389:

emulsion broke.

broken.

very poor bro N H401, percent operative in accordance with my invention,were added to these emulsions. The quality of each emulsion was judgedby noting its color, (a brown color indicating a finer grained emulsionand a black color indicating a coarser grained emulsion) and by theresults of the Sieve Test of ASTM D24455. The emulsion, in eachinstance, was allowed to stand overnight after its preparation and thenwas visually examined by stirring the contents of the storage flask orjar with a spatula, and observing the emulsion draining from the spatulaas to its color and graininess. Any settlement at the bottom of theflask and any skinning on the surface of the emulsion was likewisequalitatively examined. The quality was then noted as poor, fair, orgood. Also, a Wet Stone Dehydration and Penetration Test was employed.Results of these examinations and tests are set forth in Table I below,in which Q indicates quality and WSD & P indicates performance in theWet Stone Dehydration and Penetration test.

The WSD & P test carried out as follows:

A can is filled with clean wet siliceous aggregate containing no fines.100 grams of the test emulsion is poured over the aggregate, and themixture is cured under cool, shady conditions. After one hour, themixture is examined to determine the amount of emulsion which Q WSD A: PQ WSD dz P Q WSD & P

good poor+. do Do. i do fair.

broke very poor broke i.

Referring to Table I, wherever emulsion broke, the words Emulsion brokeor the word broke appears. Wherever an emulsion broke, as indicatedunder the espective Q column, the WSD & P test was not carried outbecause there would be no purpose in doing so.

The following is apparent from an inspection of Table I:

In most cases, the addition of ammonium sulfate and/ or ammoniumchloride improved either the quality of the emulsion, or its performancein the WSD & P test or both the quality and WSD & P performance. In somecases, the emulsion could not be prepared adequately under theconditions indicated. For example, 0.25 Hyamine 2389 was insufficient toprepare a stable emulsion, although greater quantities yielded emulsionsof poor to fair quality.

Similar improvement were obtained in similar tests employing a /200penetration San Ardo asphalt, which is a steam-refined asphalt fromcrude petroleum from the San Ardo field in California. Thus, with 0.33%Hyamine 2389 as the emulsifying agent, the emulsion (35% water, 65%asphalt) broke on agitation, but by including 0.03% ammonium sulfate, anemulsion was produced having a Q value of good and a WSD & P value offair. With 0.25% Hyamine 2389, the emulsion broke on agitation but wasimproved by 0.03% ammonium sulfate to a Q of good and a WSD & P of good.Generally similar improvements were obtained with 0.33% ADE50 asemulsifier by adding 0.03% ammonium sulfate; by adding small quantitiesof ammonium chloride to emulsions made from the same San Ardo asphaltwith I-Iyarnine 2389 as the emulsifier; and by adding small quantitiesof ammonium chloride to similar emulsions of an Inglewood 120-150asphalt having Hyamine 2389 and ADE-50 as the emulsifier.

EXAMPLE III The test series described hereinafter illustrate theoperativeness of representative salts from the group of thiocyanatesparticularly effective in accordance with my invention, namely,ammonium, sodium and potassium thiocyanates. Added in amounts from about0.01 to about 0.25% and preferably from about 0.025 to about 0.20% byweight to cationic asphalt emulsions which have been prepared withquaternary nitrogen-containing salt emulsifiers, these thiocyanates areresponsible for the simultaneous and substantial improvement of theproperties of the emulsions. Specifically, the presence of thesethiocyanates increases the emulsion stability during pumping (as shownby the Pressability data), improves stability while in storage (as shownby the Sieve Test data) and insures good adhesion of the asphalt binderto the stone aggregate.

Emulsions were prepared consisting of 70 parts by weight of Boscan200/300 penetration asphalt and 30 12 ability Test and in the StoneCoating Test, and, furthermore, reduced foaming.

EXAMPLE IV This series of tests was carried out to determine whether ornot addition of salts to the cationic asphalt emulsions, in accordancewith my invention and within the range of amounts found by me to beoperative in enhancing the pumping stability and the adhesion property,is accompanied by a lowering of the pH value of the emulsion.

Emulsions of 65% of Boscan asphalt, similar to that of Examples I andIII have been prepared, emulsifying the asphalt in water by weight) withthe aid of two representative cation-active emulsifying agents, namely,the aforementioned ADE-50 (0.5% by weight of the final emulsion) andArquad T as a 50% solution (also 0.5% by weight of the emulsion). The pHvalues of the emulsifying water were 5.10 and 6.85, respectively. The pHof the resulting emulsions were determined potentiometrically. Threetypical chlorides were introduced into the emulsions in the emulsifyingwater. These were ammonium chloride, sodium chloride and calciumchloride in amounts equal to 0.1, 0.5, and 1.0% by weight of the finalemulsion. The results appearing in the following tabulation (Table III)unmistakably indicate that addition of salts, in accordance with theinvention as described herein, has no significant effect on the pH ofthe emulsions and certainly, contrary to some previously publishedopinions, does not cause a lowering of the pH.

Table III [Emulsion pH] i No additive NHiC1, percent CaCh, percent NaCl,percent 0.1 0.5 1.0 0.1 0.5 1.0 0.1 0.5 1. Emulsion prepared with ADE-504.6 4.8 5.05 5.15 4.75 5.0 5.10 4.8 5.15 5. 20 Emulsion prepared withArquad T-50 4.75 5.05 5.35 5.35 5.15 5. 5.50 5.2 5. 5. (50

One series of these emulsions EXAMPLE V parts by weight of water.contained 0.5% of ADE-50 as the emulsifier and a second series contained0.4% of ADE50 as the emulsifier. The Sieve, Pressability and StoneCoating Tests above described were performed and the amount of foamingduring mixing with aggregate during the Stone Coating Test was noted.Results are set forth in Table II below:

Table II Boscatn 200/300 pen. asphalt (parts by 70- 70 70--." 70.--70"... 70 70.-." 70.

\V ADE-50 (parts bywt.) 0.50 8.3g.-. 0.50--- 0.40--. 0.40..- 0.40." 0.400.40.

NaSON (parts by wt.) KSCN (parts by wt.) NELSON (parts by wt.) WaterSieve test some slight shot. shot. shot shot. Pressability test(seconds) 18 40.-. 7-..- Stonecoating test (adhesioninpercent) G0 10090... 50 Foam during mixing in stone coating excessome slight.excestest. sive. sive.

ual 100 parts slight slight slight slight shot. shot. shot. shot. 30-40. 70 65. slight none none excessive.

It is seen from the data in Table II that the addition of smallquantities of sodium thiocyanate, potassium thiocyanate and ammoniumthiocyanate elfected substantial improvements in the results of theSieve Test, the Presssalts added to illustrate the operativeness of theinvention were sodium naphthalene fl-sulfonate, barium chloride andcalcium sulfate. A similar difficult-to-coat, hydrophilic, siliceousaggregate was again employed with this 13 series of emulsions in theStone Coating Test described hereinbefore. The mixing stability of theemulsions (i.e. stability while mixing with the aggregate) was comparedvisually.

Table IV 14 Emulsion A, 0.036% by weight of potassium thiocyanate;emulsion B, 0.109% by weight of potassium thiocyanate; emulsion C, 0.03%by weight of sodium thiocyanate; emulsion D, 0.061% by weight of sodiumPercent by weight of active in emulsifier material based on totalemulsion Additive salt in percent by Weight based on total emulsionMixing Stability Adhesion (percent of aggregate surface remainingcoated) EXAMPLE VI In another test, more emulsions were prepared using70 parts by weight of Boscan 200/300 penetration asphalt and 30 parts byWeight of water. The emulsifier was Nalquat G-9-13, that is,1-(2-hydroxyethy1)-2-heptadecenyl-l-(or 3)-(4-chlorobuty1) imidazoliniumchloride. The emulsifier was employed in an amount equal to 0.5% byweight of the total emulsion. Sodium acetate, as a preferred, readilyavailable additive salt, in an amount of 0.2% by weight was added to theemulsion in accordance with the invention. The acetate-containingemulsion possessed an improved pumping ability due to reduced viscosityand mixed satisfactorily with the aggregate in the Stone Coating Test.

EXAMPLE VII In this test series again the advantages of adding anacetate or a propionate of sodium have been reconfirmed. Anasphalt-in-water emulsion was prepared from 69 parts by weight of200/300 penetrating Boscan asphalt, using 0.2% by weight ofcetyltrimethyl ammonium bromide as the emulsifier, and was furthertreated with 0.1% by Weight, based on the total emulsion, of sodiumacetate. This emulsion, likewise, displayed an improvement in pumpingability, the viscosity having been reduced t less than /5 of theviscosity observed in the absence of the acetate additive. Mixing timesand adhesion were likewise improved.

EXAMPLE VIII In an additional test series again I employed emulsions of70% by weight of Venezuelan (Boscan, 200/ 300 penetration) asphalt inwater (30%), prepared with the aid of the cationic emulsifier ADE-50(0.5% by weight), mentioned among the representative quaternarynitrogencontaining emulsifier salts. Sodium and potassium thiocyanateswere added to four such emulsions (A, B, C and D), as follows:

thiocyanate. The final emulsions containing these thiocyanates, afterthey have been subjected to agitation for 30 minutes at 180190 F., hadexcellent appearance and displayed but a slight formation of asphaltshot (sedimentation).

EXAMPLE IX A series of emulsions consisting of parts by weight of200/300 penetration Boscan asphalt and 30 parts by weight of Water wasprepared with the aid of an emulsifier made up of two active cationiccomponents, namely, 0.28 by weight, based on the total emulsion ofArqua-dS (50% active), and 0.33% by weight of Rosin Amine D, and enoughHCl to react with the amine to a pH of 3.5. Arquad-S is a quaternaryammonium chloride in which the long alkyl chain is derived from soybeanoil. Rosin Amine D is the trade name of a primary amine materialmanufactured and sold by Hercules Powder Company of Wilmington,Delaware. This primary amine, as indicated by its name, containshydrocarbon radicals derived from talloil (rosin oil). To theseemulsions there were added varying amounts, from 0.025 to 0.5 by weightof the emulsion, of sodium acetate in accordance with the invention. Theso treated emulsions were then submitted to the Stone Coating Test,employing a dificult-to-coat hydrophilic, siliceous aggregate, rangingin size from /z" to l, with 5% of fines. Here the water has been appliedfive minutes after the completion of mixing. Mixing times were thenobserved and viscosities were determined.

Table V shows the results obtained in the Stone Coating Test (asadhesion in percent), the viscosity (SSE at 122 F.) and mixing times inminutes. The improvement in the mechanical (mixing) stability, in otherwords, in the ability of the emulsion to remain stable while beingapplied to the aggregate, thus permitting a satisfactory coating,isshown in Table V by the figures in Column designated Mixing Times.

Table V Additive salt Viscosity in Adhesion in Test runs in percent bySSF at 122 F. Mixing time in minutes percent Remarks 4 Asphalt residue65%. N o

cutter stock added. 1 5% of light hydrocarbon cutter stock added.Emulsion failed to coat (7- 0.1 5% of light hydrocarbon cutter stockadded. 0.025 100 Do. 0.05 100 D0. 0. 1 100 D0. 0. l 100 Do. 0.2 100 Do.0.3 100 D0. 0.5 201 ,d0 100 Do.

* Too thick to measure l,000 SSF).

The data in Table V again clearly indicate that the addition of a saltin accordance with the invention results in a satisfactory stablecoating on the aggregate (as shown by the values of adhesion), and,furthermore, markedly improves the mechanical stability of the emulsion.The fact that the mixing time available for an intimate mixing andcoating of the aggregate with the emulsion is increased so markedly,represents a very valuable advan tage in those applications where theemulsions are mixed with the aggregate at the job site in the so-calledmotopaver equipment (described, e.g., in Bulletin MP-49 of Hetheringtonand Berner, Inc. of Indianapolis, Indiana), and the mix is thereafterimmediately applied to the road bed. Furthermore, the addition of asalt, such as sodium acetate, as shown in the present test series,occasions a lowering of viscosity and improves thereby the pumpingability of the emulsions.

EXAMPLE X This test series was carried out to demonstrate again that theaddition of acetates and propionates to cationic asphalt emulsions inaccordance with the invention tends to impart to these emulsions a lowerviscosity, to improve their stabilities in storage and in pumping, andto assure effective mixing thereof with, and coating of hydrophilicsiliceous aggregates.

In the tests of similar emulsions of 70 parts by weight of 200/300penetration Boscan asphalt and parts by weight of water, using about0.4% by weight of Arquad T as the emulsifier, addition of sodium acetatein the same range of amounts from 0.025 to 0.5% by Weight of theemulsion, shows an improvement (lengthening) of mixing times, asatisfactory coating of the aggregate, and an adequate stability forsurviving the pumping action before the actual application of theemulsion in paving work.

The aforegiven description, illustrated by the experimental data, makesit apparent that a new and effective means has been provided forimproving cationic emulsions with respect to emulsion quality (e.g.,more uniform particle size and the descreased proportion of large oroversized particles), and with respect to performance qualities, such aspumping qualities, Stone Coating (adhesion), etc.

I claim:

1. An oil-in-water type cationic asphalt emulsion for use in pavingapplications, characterized by its ability to be pumped without breakingdown and by remaining stable for at least five minutes on being mixedwith siliceous stone aggregate, said emulsion consisting essentially (a)from about 30 to about percent by weight of asphalt as the dispersedphase;

(b) from about 0.25 to about 1.5 percent by weight of a quaternarynitrogen-containing compound characterized by the general formula inwhich the organic radicals R R R and R are alkyl, alkenyl, hydroxyalkyl,arylakyl, and alkylaryl radicals of 1 to 24 carbon atoms, andheterocyclic groups of 4 to 10 carbon atoms, in which from 2 to 3 of thenitrogen valences are shared by 2 carbon atoms in a single heterocyelicgroup, and X is an anion selected from the group consisting of chlorideand bromide anions; (c) from about 0.01 to about 0.25 percent by weightof a water-soluble alkali metal acetate; (d) water as the continuousphase in an amount to make up percent. 2. An oil-in-water type cationicasphalt emulsion as defined in claim 1, wherein the water-solublealkali-metal acetate is sodium acetate.

References Cited by the Examiner UNITED STATES PATENTS 1,960,115 5/1934Loebel 106-277 XR 2,191,295 2/1940 Dohse et al 106-273 XR 2,615,85110/1952 Manzer 252-3115 FOREIGN PATENTS 702,818 1/ 1954 Great Britain.

JULIUS GREENWALD, Primary Examiner.

ALBERT T. MEYERS, Examiner.

1. AN OIL-IN-WATER TYPE CATIONIC ASPHALT EMULSION FOR USE IN PAVINGAPPLICATIONS, CHARACTERIZED BY ITS ABILITY TO BE PUMPED WITHOUT BREAKINGDOWN AND BY REMAINING STABLE FOR AT LEAST FIVE MINUTES ON BEING MIXEDWITH SILICEOUS STONE AGGREGATE, SAID EMULSION CONSISTING ESSENTIALLY OF:(A) FROM ABOUT 30 TO ABOUT 70 PERCENT BY WEIGHT OF ASPHALT AS THEDISPERSED PHASE; (B) FROM ABOUT 0.25 TO ABOUT 1.5 PERCENT BY WEIGHT OF AQUATERNARY NITROGEN-CONTAINING COMPOUND CHARACTERIZED BY THE GENERALFORMULA